Device for retreading tires



April 14, 1953 J. H. F. KENT 2,634,492

DEVICE .FOR RETREADING TIRES Filed March 9, 1948 7 Sheets-Sheet 1 4450 i-l E April 14, 1953 J. H. F. KENT 2,634,492

DEVICE FOR RETREADING TIRES Filed March 9, 1948 7 Sheets-Sheet 2 April 14, 1953 J. H. F. KENT 2,634,492

DEVICE FOR RETREADING TIRES Filed March 9, 1948 7 Sheets-Sheet 5 April 14, 1953 J. H. F. KENT 2,634,492

DEVICE FOR RETREADING TIRES Filed March 9, 1948 7 sneets-sheet 4 April `14, 1953 J. H. F. KEN1' DEVICE FOR RETEEADING TIRES -7 Sheets-Sheet 5 Filed March 9, 1948 J. H. F. -KENT DEVICE FOR RETREADING TIRES Ap 14, E953 7 Sheets-Sheet 6 Filed March 9,' 1948 fam/mf Mw 5. w/Wig# -APYB 4, 1953 J. H. F. KENT 2,634,492

y DEVICE FOR RETREADING TIRES Filed Mehk, 1948 '7 Sheets-Sheet 7 g-Mw@ f Patented Apr. 14, 1953 DEVICE Fon RETREADING TIRES Jan Herbert Farquharson Kent, Worting, Basingstoke, England, assigner of one-halfto Auto Tyre Services Limited, Worting, Basingstoke, England, a company of Great Britain Application March 9, 1948,`Serial No.,13,928

f In Great Britain March 20, 71947 4 Claims.

1 This invention relates to improvements in tire rasping or buiiing machines designed lto modify the tread of the tire, which hereinafter is referred to as detreading. In the process of retreading tires, vit is necessary before applying the new (unvulcanized) tread rubber to resp Vthe tread surface of the worn tire, firstly in order to remove inequalities and secondly to leave a roughened surface for the new tread to adhereto.

In doing this work on a production basis, difculties arise by reason of the many diierent (Cl. Z9-76) sizes of tires and varying curvatures Ain the types I of tire sections encountered, necessitating either a number of curved rasps, which have to be changed to suit each individualtire, or the taking of a number of cuts at different angles usiner a straight rasp.

This invention has for its object t0 provide an improved detreading machine which will enable the tread of the tirerto be shaped to an?)7 desired. section by a single cutting operation, once the tire carcass has been set up in the machine.

A further object of the invention is to provide a detreading machine .in which the detreading operation, once the machine has been started up, becomes more or less automatic in that it is under the control `of a single lever Which sets the depth or amount of cut. Y l

Broadly stated, the present invention consists in combining with the rasping machine, a device adapted b y engagement ,withY the beads orwalls of the tire to separate them and thus modify vthe contour of the tread, such as by, flattening it, so that whileit is subjected t0 the action of the rasp, it possesses thesame or Substantially the same cross section as the rasp itself, regardless of the original transverse radius 'of the tread.

In this manner it is possible to reduce the cross section of the tread to a plane or concave surface, or to whatever other contour is required; this makes it possible to use the Same rasp or brush irrespective of the size of the tire or curvature thereof undergoing repair. On release of the pressure on the beads `after rasping, the tire will assume its normal curvature again. The device of this invention thus overcomes the necessity of changing contour rasps. or taking a number of individual cuts at different angles on a straight rasp.

According to this invention a machine for modifying, by cutting, the tread of a tire comprises means for supporting the tire to revolve about its centre, means for applying pre'r'ssure to the walls of the tire to force them 'apartt'o pro duce a flattening at lthe tread, said means be-y ing movable into and out of engagement With the tire, and cutting means adapted to make a out on the tread when in a flat or similar Condition by causing the l'tire to be moved past the cutting means.

Apparatus for carrying out the invention comprises a main frame, a set of rollers to support the tire so as to be capable of revolving about its centre, a subassembly mounted on the main frame movable to and from a position centrally within the centre of the tire, and nger elements carried by the subassembly and adapted when said assembly is in position to engage with the tire to force the beads vapart to produce a flattening at the tread, and cutting means movable into and out of engagement with the tread to apply the desired cut thereto when attened.

In order to center the tire in relation to .the rollers, means, such as levers, may be provided movable into and out of engagement with the side walls of the tire so -as to shift the 'tire bodily to a central position. Other ymeansy preferably opposite pairs of rollers, may be -provided to maintain the tire positioned in `a vertical plane in relation to the support rollers. These guide rollers may be movable to and from a central .position where they are positively held so as to engage the tire at a point on its circumference opposite to the support rollers, and are so constructed and arranged that when withdrawn they dogfnot interfere with the placing of a tire in position on the support rollers.

The invention is illustrated in the accompany# ing drawings in which: l

Figure 1 is a side view vof the machine con structed according to the invention showing a tire (in dotted lines) in position.

Figure 2 is an end view corresponding te Figure 1 with the linger elements for moving the beads apart in their operative position.

Figure 3 is a diagrammatic view showing the tire in cross section with the linger elements in position before and after displacement of the beads.

Figure 4 is an enlarged View of vthe lower part of Figure 2 showing the tire supporting and revolving rollers in detail.

Figure 5 is a side view corresponding to Figure 4.

VFigure 6 Ais an enlarged view of the middle part of Figure 1 showing the subframesupporting the ng'ereleme'nts forming part of the tire distending mechanism.

Figui-es? and Sare'respectively a vertical see-1 tion and sectional plan view of the'r tire distanti"v ing mechanism of Figure 6 and its method 0f operation.

Referring to Figure 3 of the drawings, A indicates a tire shown in cross section, the tread B of which is to be subjected to the action of a rasp to remove inequalities and to provide a roughened surface to facilitate adhesion of the new tread to be built up thereon.

The method of this invention essentially consists in spinning the tire circumferentially during such time as the tire is held by a series of rollers to prevent movement of the tire laterally, including a vertical set of rollers indicated diagrammatically at C and while its beads D are spread apart by means oftire distending mechanism -incorporating pressure Aapplying nger elements E, E. When in this position a cutting tool e. g. a rasp indicated at R, is brought into engagement with the tread, the surface of which will now be substantially flat, the ratp rotating about an axis in a plane parallel to the axis of rotation of the tire. v

A machine capable of performing the rasping operation and centering the tire on its supporting rollers is shown in Figures 1 and 2. The machine comprises essentially a subframe F, under the control of a cylinder K, supporting the finger elements E, the whole frame being withdrawn so that a tire to be processed can be rolled or otherwise placed in position, shown in dotted lines in Figure 1, where it rests o'n rollers I, 2. When in position on rollers I, 2, the tire is centered and held laterally by two opposite sets of rollers, indicated generally at H, under the control of a ram J, the ram J remaining operative during the rasping operation so that the tire is centered and held vertically in relation to the face of the rasp R.

The next step inthe operation, assuming the tire has been centered by rollers I-I, is for the subframe F, through a second ram M, to be moved into position within the center of the tire so that the iinger elements E, E (see Figure 2) are in alignment kwith the opening between the beads D of the side walls of the' tire. Having been so positioned, this frame is now lowered and when in position, as shown in Figure 3, the two finger elements E-E' are moved apart from one another to the dotted line position shown, thereby forcing the beads apart and so causing a nattening of the tire at the tread. The rasp R which is carried by another subunit N (see Figure 2) is now lifted to contact the tread of the tire.

It will be appreciated that the rasp'is raised until the requisite cut on the tire is obtained after which the rollers I, 2 which are separately connected to a small horsepower motor (not shown) are rotated until the tire has done a complete revolution past the rasp. The operations just described are now repeated in reverse sequence andthe tire pushed ofi the roller 2 ready for the next tire. K

. The machine'shown in Figures 1 and 2 comprises a vertical cage having pairs of uprights Il, 5 spaced apart from one anothento provide a central passage 5, into which the tire can be wheeled up a ramp 3 and in to position on the support rollers l, Y2 which are now stationary. The uprights Il, 5, 5, are connected by laterals l, 8, 9 and 'are spaced apart from one another at their upper end by transverse straps YTo afssist'inV centering a tire, which has been positioned on the rollers I, 2, there are preferably providedV twoopposite pairs of rlever arms II-II and I2-I2 (see Figure 4) mounted to rock about lateral horizontal axes I3 provided in brackets attached to each pair of uprights Ii, 5. Movement of the lever arms II, I2 is controlled by a foot pedal I4 fast on an axis I5 to which is also secured a two armed lever I5 connected to the opposite ends of which are rods I'I, I8 coupled through straps I9 to one of each of the lever arms II, I2. Pressure on the foot pedal Iii will. rock the lever I6 thereby displacing the upper ends of arms II, I2, in the direction of the arrows with the object of centering the lower portion of the circumference of the tire in relation to the rollers I, 2. Each pair of arms II, I2 is interconnected by means of rods 20, 2| so as to engage the lower circumference of the tire across a chord and thus properly center it in relation to the rollers I, 2.

The operation and actuation of the rollers H which are arranged in two oppositely acting pairs 3--3Il and 3I -3I can best be seen in Figures 1 and 2. Each roller is mounted to rotate about an inclined axis r--r radial to the center of rotation of the tire, being freely mounted to revolve between U-shaped brackets 32 rigid with displaceable'supp'orts 33. The brackets 33 aredisplaceable laterally from the open or withdrawn position shown in Figurev 2 in the direction of the arrows S corresponding to the movement of the centering rods 25, 2I so as to co-operate therewith in centering the tire but whereas the rods 2B, 2i are withdrawn once the tire is centered i. e. during the rasping operation, the rollers 35, SI remain locked in position to hold the tire in a vertical plane. Each of the four brackets 33 is supported by means of a parallel link motion including a link 34 anda lever 35 attached at their lower ends 36, 31 to angle brackets indicated generally at 38 carried on the laterals 5. The links Sli operate as a simple link but the lever arms B5 form one arm of a bell crank lever 39, whose other arm is connected at 40 to an actuating rod Ill. Itwill be noted that thebell cranks 39 are bent in as at 39' and are connected to one another by a pin lill', on which the lower end of the actuating rod 4I is journalled.

The upperends ofthe actuating rods 4I, 42 are provided with straps 43 for connection to short armed levers i4 fast on rock shafts t5, t6. Each of the shafts 45, d6 are journalled to rotate in bearing housings :l1 attached to the transverse members IIJ. Centrally connected to the shafts t5, 46 are levers 48 whose upper ends 49 are secured by means of a pin 50 to thepiston 5I of the actuating ram J. Y

It will be obvious that on admitting fluid pressure to the cylinder of ram J, the rod 5I will move downwardly and thereby rock the shafts 45, 46 so transmitting motion through lever arms M to the links 4I rand thence to the bell crank arms 35 which will displace the brackets 33 inwardly in the direction of the arrows S so that the rollers 30, 3I thereon will press against the side walls of the tire.

Referring now more particularly to Figures 6, 7 and 8 there is shown in detail the subframe F including the spreader finger elements E, E for engaging and separating the side walls of the tire as already described in connection with Figure 3. Secured to the lateral members 'I and 8 are two vertical columns 6G on which are slidable pairs of collars 5I, 52, these collars as is clearly shown in Figure 6 being integral with side plates 63 which are connected by an inverted channel 54. l.Vertical vmovement of the subframe'isvcontrolled by vmeans of the hydraulic'ram M (see Figure 1), which is mounted on the lateral 8, the piston rod'having an extension 65 by means of which it is coupled to an anchorage 55' on the channel piece 611. Thus the subframe supporting the finger elements E, E' can be lowered into position when centrally above the opening between the beads. Mounted between the side plates 63 of the subirame is a swinging carriage comprising two underslung arms BE having laterally offset lower ends 61, pivotally attached by means of studs 68 to lugs 68 on the side plate 63. Extending at right angles tor arms vSli, and when the latter are in their op'erativeposition '(see Figure 7) inwardly of the main frame are limbs 66 which are joined at their outer ends by a brace plate 59, the arms 56 being spaced by a corresponding brace plate 69. Support'- ed by limbs 6B is a platform 10, the under'- side of which forms a lthrust surface as hereinafter described. Journalled in bearings 1I, 1 I 12, 12 in the plates 69, 6H are spindlesw13, 14 which are provided with screw threads 13', 14 over a portion of their length. Mounted on spindles 13, 14 are hub blocks 15, each of which blocks i5 is formed with a shoulder 1B for Amounting a roller 11, the rollers as clearly shown in Figure 3 operating to engage the inner perimeters of the beads of the tire. The bore of each block is also screwed to engage the screwed portions 13', 14 of the spindles, so that rotation of the latter will cause the blocks to be traversed lengthwise of their respective spindles, each block being held against rotation by engagement with vthe underside of platform 1li. l 5

On the underside of the hub bloclis iare drilled holes 18 .to receive studs v19.! each stud mounting by means ofball bearings a conical roller 8D, the rollers Si) functioning as nger elements for engagement with'the tire beads asvillustrated by Figure 3. l

llt will be seen in Figure 8 thatythenspindles 13, 'i4 are extended beyond the platemember A39 and coupled to each other by intermeshing toothed wheels V82, 83 so that they Iwill revolve in opposite directions, one ofthe spindles 1li beingprovided with a bevel pinion'l. Normally disengaged with the bevel pinion 314 is a smaller bevel fast on a shaft 86, which shaft $5 is 'slidably and rotatably mounted in a sleeve member 83 carried by the right-hand side plate B3. The shaft 8E .is normally held by means of a spring 39 in a position where the bevel 85 is out of engagement with pinion 84, a crankfhandle 9S being mounted on its outer end. so the shaft can be forced inwardly i against the action oi spring S5 to bring bevel pinions 84, 85 into driving engagement with one another. It will thus be seen that pinions M585 operate both as a clutch and means ci imparting drive to the spindles '53, lei. When this takes place, by reason of the fact that the spindles are coupled for opposite rotation the'blocks .15 will be moved in opposite directions from the position shown in Figures' and 8 where they are inalignment with one another to that shown in dotted lines (see Figures 2 and '3)'.

The side plates 63 as clearly shown in Figure 'i comprise outwardly extending portions 63' 'which at their upper ends are bent inwardly to form bracket arms Si connected by a strap 92. strap S2 functions as a trunnion for a mounting 93 for a hydraulic cylinder ed having a ram d5 for swinging the carriage 'i-l-Si! into and out of a position centrally of the tire.

The piston 95, for this purpose has its piston rod The 1H 96 'connected by a stirrup piece 91 to a cross bar .93 secured at its outer ends to the arms v99 of a pair uof bell crank vlevers i60. ihe bell crank levers 99 are mounted on trunnion pins IGI in the extensions 53 of the side plates-83, their other arms H12 being connected through llinks |03 to studs i134 on the arms 56 which form part of the swinging carriage carrying the elements E.

In operation therefore, when the upper sets of rollers H have been moved into position `to engage a tire, fluid pressure is admitted to the cylinder Bti so as to dispiace the piston 95 and swing the arms S1 from their outwardly inclined position (shown in dotted lines in Figure 7) to the vertical positionk where the limbs 66 with the platform 1i] extending horizontally above the tire cavity, (as in Figure 7).

The next operation is to lower the subframe lcomprising the plates V63 and collars 62 downwardly on the columns te by means of the ram M so that the rollers Se enter the interior of the tire D as shown in Figure 3. Y 7

The cutting tool R v(see Figure 5) preferably comprises a rotary wheel i i having blades or teeth mounted to revolve on a spindle Hl supported at its'ends in bearings H2 formed in the side arms H of a saddle member U3. On the side arms lil-l are iiats H5 for'engagement with vertical bearing faces l i6 machined in upstanding brackets H1 attached to the base H8 supporting the uprights 1i, 5.

As' previously described the rasp I I0 ismovable into and out or engagement with the tread of the tire by means of a screw jack, not shown, so that the requisite amount of cut can be made onv the tread,` the tire being caused to revolve by means 'of rollers i and 2. i

It will be understood that the various operations of the machine may be controlled automatically and for this purpose the several ram or other power actuated means for raising and lowering the subframe, actuating the swing assembly thereon, controllingand locking centraln izing rollers 3U, actuating centralizing levers 2e, imparting displacement to rrasp R, starting and stopping the drive to the support rollers, l, 2 and/orto rasp R may be intercoupled and controlled through a single control mechanism V.or valve so that the'machine becomes fully automatic. The movement of the finger element EE' may' also be carried out vby power instead of the manual 'meansshownv Y jwhatr claimis:

.1. In lapparatus .for modifying by cutting .the tread of a tire, `a main frame having uprights providing Van interior opening, at least two rollers on said frame adjacentthe base of said opening-l vto support a tire within the opening so as to be capable of revolving about its own center by power applied to the tire tread through one of said rollers, guide rollers supported by the frame so as to Vbe capable of movement linto and out of engagement with opposite sides of the tire, which rollers are normally positioned so as to permit unrestricted entry of a tire to the tire opening, a subirame supported byY said main frame, said subframe having a carriage, said carriage comprising a pair of spaced arms pivotally mounted on the subframe and a platform joining and being carried by said arms, a pair of parallel spindles mounted on said carriage, ringer elements, non-rotatable blocks carrying said finger elements and. being traversible on said spindles, the pivotal mounting of said arms enabling movement of' said subyengagea frame to and from a relatively stationary position `overlying the inner perimeter of the tire, said linger elements being operative in the latter position to spread the tire at its opening through revolving of the tire relatively thereto, said nger elements being relatively iixed in the operative position so as to be capable of relative displacement, and means for moving the subframe to and from a position with the iinger elements between the beads of the tire.

2. In apparatus for modifying by cutting the tread of a tire, a main frame having upriglits providing an interior opening, at least two rollers on said frame adjacent the base of said opening to support a tire within the opening so as to be capable of revolving about its own center by power applied to the tire tread through one of said rollers, guide rollers supported by the frame so as to be capable of movement into and out of engagement with opposite sides of the tire, which rollers are normally positioned so as to permit unrestricted entry of a tire to the tire opening, a subframe supported by said main frame, said subirame having a carriage, said carriage comprising a pair of spaced arms pivotally mounted on the subrame and a platform joining and being carried by said arms, a pair of parellel spindles mounted on said carriage, finger elements, non-rotatable blocks carrying said iinger Velements and being travers- Vbeing in the form of conical rollers mounted on said studs, the pivotal mounting of said arms enabling movement of said subframe to and from a relatively stationary position overlying the inner perimeter of the tire, said iinger elements being operative in the latter position to spread the tire at its opening through revolving of the tire relatively thereto, said finger elements being relatively iixed in the operative position so as to be capable of relative displacement, and means for moving the subframe to and from a position with the iinger elements between the beads of the tire.

3. In apparatus for modifying by cutting the tread of a tire, a main frame having uprights providing an interior opening, atleast two rollers on said frame adjacent the base of said opening to supporta tire within the opening so as to be capable of revolving about its own center by power applied to Vthe tire "tread through one of said rollers, guide rollers supported by the frame so as to be capable of movement into and out of engagement with opposite sides ofthe tire, which rollers are normally positioned so as to permit unrestricted entry of a tire to the tire opening, a 1subframe supported by said main frame, said subframe having a carriage, said carriage comprising a pair of spaced arms pivotally mounted on the subframe and Va platform joining and being carried by said arms, a pair of'parallel threaded spindles mounted on said platform, iinger elements, blocks carrying said finger elements having threaded engage.-

' ment with said spindles vand being traversible by rotation of said spindles, said blocks engaglil ing said platform to prevent turning of the blocks, the pivotal mounting of said arms en abling movement of said subframe to and from a. relatively stationary position overlying the inner.perimeter of the tire, said finger elements being operative in the latter position to spread the tire at its opening through revolving of the tire relatively thereto, said linger elements being lrelatively fixed in the operative position so as to be capable of relative displacement, and means for moving the subframe to and from a position with the iinger elements between the beads of the tire.

4. In apparatus for modifying by cutting the tread of a tire, a main frame having uprights providing an interior opening, at least two rollers on said frame adjacent the base of said opening to support a tire within the opening so as to be capable of revolving about its own center vby power applied to the tire tread through one of said rollers, guide rollers supported by the frame so as to be capable of movement into and out of engagement with opposite sides of the tire, which rollers are normally positioned so as to permit unrestricted entry of a tire to the'ftire opening, a subframe support `by said main frame, said subframe having said carriage comprising a pair of cv l pivotally mounted on the subframe a I"'a..plat. form joining and being carried by said arms, 7a

pair of parallel threaded spindles mounted on said platform, finger elements, non-rotatable sliding blocks on which said 'finger elements are mounted having threaded engagement with said spindles and being traversible by rotation of said spindles, means coupling said spindles to rotate in unison, operating means normally disconnected from said spindles but being connectable therewith for rotating the spindles, the pivotal mounting of said arms enabling movement of said subframe to and from a relatively stationary vposition overlying the inner perimeter of the tire, said nger elements being operative in the latter position to spread the tire at its opening through revolving of the tire relatively thereto, said iinger elements 4being relatively fixed in the operative position so a be capable of relative displacement, Ia eans for moving the subframe to and from a osition with the finger elements between the beads of the tire.

JAN HERBERT FARQUHARSON KENT. Y

References cited in the aie of this parent UNITED STATES PATENTS Number Name Date 1,426,910 Replogle Aug. 22, 1922 1,517,278 Case Dec. 2, 1924 1,713,488 Grundmark May 14, 1929 1,745,021 Liebau Jan. 28, 1930 1,868,764 Prentice Jan. 21, 1932 1,886,834 Prentice et al. a Nov. 8, 1932 1,916,258 Errig et al July 4, 1933 2,105,316 Fleming Jan. 11, 1938 2,173,795 Fisher Sept. 19, 1939 2,254,526V Hawkinson Sept. 7, 1941 2,321,936 Pollock June 15, 1943 

